They’d just do the same thing anyone does when the want to obscure their home IP. Just use VPNs, route though sympathetic counties, or other ways to hide who you are. It’d just be a constant game of whack-a-mole. Why do you think we can’t just block people who hack our infrastructure or companies can’t so easily block data thieves? If all it took was blocking a couple addresses or a range it would be easy.